Southland Is Buffeted by Winds Gusting Up to 60 M.P.H. : Weather: Santa Anas knock down power poles, fan two fires and wreak havoc with commuters.

Gusty Santa Ana winds whipped through Southern California on Wednesday, knocking down power lines, creating airborne traffic hazards and sparking at least two fires.

In San Diego County, the National Weather Service reported wind gusts of more than 40 m.p.h. in some mountain and inland valley areas, temporarily knocking out power to an estimated 90,000 San Diego Gas & Electric Co. customers. As of late Wednesday, power had been restored to all but about 5,000 of those homes, SDG&E; spokesman Fred Vaughn said.

Most of the outages were caused by power lines being downed either by the winds or by broken tree branches, Vaughn said.

The California Highway Patrol also issued high-wind warnings along portions of Interstate 8 in eastern San Diego County and for Interstate 5 from Oceanside to the Orange County border.

Wilbur Shigehara, the Weather Service’s chief meteorologist in San Diego, said the high winds are expected to continue through today, gradually dissipating by mid-afternoon.

In the northeast San Fernando Valley, winds reached 60 m.p.h. early in the morning, snapping 13 power poles, according to the Los Angeles Department of Water and Power. About 4,000 customers in Sylmar and Pacoima were left without electricity.

While homeowners dealt with loosened roof shingles and tiles and rattling windows, commuters from the San Fernando Valley to Riverside dodged flying palm fronds, fallen tree limbs and tumbleweeds that bounced in the air like jugglers’ balls.

In Malibu, the Los Angeles County Fire Department reported that a five-acre blaze started when a car crashed into a telephone pole in Malibu Canyon and sparked nearby brush. And in the Saddleback Mountain area of Orange County, a wind-fanned brush fire briefly caused anxiety but was contained after scorching just four acres, officials said.

A utility pole downed by wind near Pacific Coast Highway in Malibu left 145 customers, including parts of Pepperdine University, without power for two hours, a spokesman for Southern California Edison Co. said. In Orange County, more than 7,000 customers had service interrupted, mainly in Costa Mesa and Santa Ana. Several people were stranded in a Costa Mesa City Hall elevator for about an hour, officials said.

Wind blew down fencing along the center divider in several sections of Interstate 15 in Riverside County, the California Highway Patrol reported, but traffic was not impeded. Waves of wind-borne dust and debris slowed motorists to 5 m.p.h. in some sections of Interstate 10 between Ontario and San Bernardino.

“We’re advising extreme caution,” CHP spokesman Mark Mezzano said.

The CHP issued travel warnings for campers and trailers throughout the Inland Empire and on all freeways north of California 118 to the Grapevine, including the Antelope Valley.

The wind played a practical joke on some Orange County motorists Wednesday morning, causing them to believe that part of the Santa Ana Freeway was closed, the CHP said. The wind blew off a canvas flap on a sign about an upcoming temporary closure near the El Toro “Y” interchange. Motorists seeing the sign made a detour onto the San Diego Freeway, intensifying the usual bottlenecks on that freeway.

On Norris Street in Pacoima, two unoccupied cars became stuck under an old tree that was uprooted by the wind and fell across them, breaking their windows and flattening their tires.

Winds of 20- to 40-m.p.h. were expected to continue today, with gusts “pretty common around 50 m.p.h.,” said Marty McKewon, meteorologist with WeatherData Inc., which provides forecasts for The Times. “But . . . I think we’ll see a decrease in the afternoon.”

The National Weather Service said the winds were being caused by a high-pressure center stalled over Idaho and Nevada.

Times staff writers Barry Horstman in San Diego, Julio Moran in Los Angeles, Joanna Miller in Ventura County, Jenifer Warren in Riverside County and Bill Billiter in Orange County contributed to this story.